Polyimide-forming compositions, methods of manufacture, and articles prepared therefrom
View Patent ↗A polyimide-forming composition includes a particulate polyimide precursor composition having an average particle size of 0.1 to 100 micrometers wherein the polyimide precursor composition comprises a substituted or unsubstituted C 4-40 bisanhydride, and a substituted or unsubstituted divalent C 1-20 diamine; an aqueous carrier; and a surfactant. A method of manufacturing an article including a polyimide includes the steps of forming a preform comprising the polyimide-forming composition; and heating the preform at a temperature and for a period of time effective to imidize the polyimide precursor composition and form the polyimide. An article prepared by the method, and a layer or coating including a polyimide and a surfactant are also described.
1. A method of manufacturing an article comprising a polyimide, the method comprising
forming a preform comprising a polyimide-forming composition comprising:
a particulate polyimide precursor composition having a maximum particle size of 100 micrometers or less, for example 0.01 to 100 micrometers, wherein the polyimide precursor composition comprises
a substituted or unsubstituted C 4-40 bisanhydride, and
a substituted or unsubstituted divalent C 1-20 diamine;
an aqueous carrier; and
a surfactant;
the method comprising:
heating the preform at a temperature and for a period of time effective to imidize the polyimide precursor composition and form the polyimide;
wherein the polyimide has less than 1 wt % organic solvent.
2. The method of claim 1 , wherein the forming is by spinning, spraying, casting, coating a surface of a substrate, impregnating a porous substrate, coating a surface of a mold, or disposing the polyimide-forming composition in a mold.
3. The method of claim 1 , further comprising removing the aqueous carrier from the preform before or during the heating to imidize the polyimide precursor composition.
4. The method of claim 1 , further comprising crosslinking the polyimide before, during, or after the imidizing.
5. The method of claim 1 , wherein the article comprising the polyimide is a fiber, a layer, a conformal coating, a composite article, a composite molded article, or a molded article.
6. The method of claim 1 , wherein the particulate polyimide precursor composition has a D100 particle size of 75 micrometers or 45 micrometers.
7. The method of claim 1 , wherein the particulate polyimide precursor composition comprises separate particles of the bisanhydride and the diamine.
8. The method of claim 1 , wherein a mole ratio of the bisanhydride to the diamine is 1:1 to 1:1.3.
9. The method of claim 1 , wherein a mole ratio of the diamine to the bisanhydride is 1:1 to 1:1.3.
10. The method of claim 1 , wherein the aqueous carrier comprises less than 1 wt % of a chlorobenzene, a dichlorobenzene, cresol, dimethyl acetamide, veratrole, pyridine, nitrobenzene, methyl benzoate, benzonitrile, acetophenone, n-butyl acetate, 2-ethoxyethanol, 2-n-butoxyethanol, dimethyl sulfoxide, anisole, cyclopentanone, gamma-butyrolactone, N,N-dimethyl formamide, N-methyl pyrrolidone, or a combination comprising at least one of the foregoing.
11. The method of claim 1 , wherein the surfactant is nonionic.
12. The method of claim 1 , wherein the polyimide-forming composition comprises, based on the total weight of the composition,
1 to 90 wt % of the particulate polyimide precursor composition;
10 to 99 wt % of the aqueous carrier, and
0.001 to 10 wt % of the surfactant.
13. An article prepared by the method of claim 1 .
14. The article of claim 13 , wherein the article is a layer or coating comprising the polyimide and from 0.001 to 5 wt % of a surfactant, wherein the layer or coating has a thickness 0.1 to 1500 micrometers.